MPTP is a pseudosubstrate for the copper oxidase ceruloplasmin, and both MPDP+ and MPP+ are produced. Incubation of MPTP with horseradish peroxidase only provided MPTP N-oxide. Oxidation of MPDP+ and MPP+ with potassium ferricyanide afforded a dihydropyridone and a pyridone respectively. MPTP analogs derived from prodine-type analgesics were found to be devoid of neurotoxic properties. A series of deuterated MPTP-analogs was prepared and their inhibitory effects on MAO B measured.